Detection of elevated levels of her-2/neu protein on circulating cancer cells and treatment

Abstract

The expression of Her-2/neu protein on circulating cancer cells in a blood sample is detected by isolating the cancer cells from the blood sample and then performing on the isolated cancer cells a sensitive Her-2/neu immunoassay. A positive result indicates the expression of Her-2/neu on cancer cells in the blood sample. This method can be used to identify cancer patients who are likely to benefit from treatment with an anticancer agent that targets Her-2/neu, such as trastuzumab (HERCEPTIN).

1 . A method of detecting the expression of Her-2/neu protein on circulating cancer cells in a blood sample comprising isolating the cancer cells from the blood sample, lysing the isolated cancer cells to yield a cell lysate, followed by performing on the cell lysate an immunoassay capable of detecting cancer cell-associated Her-2/neu, in which a positive immunoassay result indicates the presence of Her-2/neu on the cancer cells;
 wherein the cancer cells are isolated by contacting the blood with immunomagnetic beads capable of binding selectively to the cancer cells;   the immunoassay uses the detection technique of electrochemiluminescence;   the immunoassay uses two antibodies that bind selectively to Her-2/neu;   and the immunoassay has a sensitivity defined by:   a) being capable of detecting cancer cell-associated Her-2/neu at a level of between one-tenth and twenty picograms of Her-2/neu per milliliter of the blood sample; or   b) being capable of detecting Her-2/neu from SK-BR-3 breast cancer cells when spiked into blood at a concentration of less than or equal to 100 SK-BR-3 cells per milliliter of blood.   
     
     
         2 . The method of  claim 1 , wherein the sensitivity level in a) is between one and twenty picograms of Her-2/neu per milliliter of the blood sample. 
     
     
         3 . The method of  claim 2 , wherein the sensitivity level in a) is between one and ten picograms of Her-2/neu per milliliter of the blood sample. 
     
     
         4 . The method of  claim 3 , wherein the sensitivity level in a) is between one and five picograms of Her-2/neu per milliliter of the blood sample. 
     
     
         5 . The method of  claim 1 , wherein the sensitivity level in b) is less than or equal to 10 SK-BR-3 cells per milliliter of blood. 
     
     
         6 . The method of  claim 5 , wherein the sensitivity level in b) is less than or equal to 3 SK-BR-3 cells per milliliter of blood. 
     
     
         7 . The method of  claim 6 , wherein the sensitivity level in b) is less than or equal to 1 SK-BR-3 cell per milliliter of blood. 
     
     
         8 - 12 . (canceled) 
     
     
         13 . The method of  claim 1 , wherein the immunoassay uses two antibodies that bind selectively to the cytoplasmic domain of Her-2/neu. 
     
     
         14 . The method of  claim 1 , wherein the immunoassay uses a polyclonal antibody against Her-2/neu. 
     
     
         15 . The method of  claim 1 , wherein the immunoassay uses a monoclonal antibody against Her-2/neu. 
     
     
         16 . The method of  claim 15 , wherein the monoclonal antibody is a humanized mouse monoclonal antibody. 
     
     
         17 . The method of  claim 16 , wherein the monoclonal antibody is trastuzumab. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 1 , wherein the immunomagnetic beads bind selectively to epithelial cells. 
     
     
         20 - 22 . (canceled)